Belt or fabric including polymeric layer for papermaking machine

ABSTRACT

A fabric or belt for a papermaking machine including a first layer that defines a web contacting surface and a second layer that supports the first layer. The first layer is made of extruded polymer and includes a plurality of first elements aligned in a first direction, a plurality of second elements aligned in a second direction and extending over the plurality of first elements, and a plurality of open portions defined by the plurality of first and second elements. The second layer is made of woven fabric. The first layer is bonded to the second layer so that the first layer extends only partially through the second layer and an interface formed between the first and second layers includes bonded and unbonded portions and airflow channels that extend in a plane parallel to the first and second layers.

RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.15/431,497, filed Feb. 13, 2017, now U.S. Pat. No. 10,208,426, andentitled BELT OR FABRIC INCLUDING POLYMERIC LAYER FOR PAPERMAKINGMACHINE, which in turn is a non-provisional based on and claimingpriority to U.S. Provisional Patent Application No. 62/294,158, filedFeb. 11, 2016, and entitled BELT OR FABRIC INCLUDING POLYMERIC LAYER FORPAPERMAKING MACHINE, the contents of which are incorporated herein byreference in their entirety.

FIELD OF THE INVENTION

This disclosure relates to fabrics or belts for a papermaking machine,and in particular to fabrics or belts that include polymeric layers andthat are intended for use on papermaking machines for the production oftissue products.

BACKGROUND

Tissue manufacturers that can deliver the highest quality product at thelowest cost have a competitive advantage in the marketplace. A keycomponent in determining the cost and quality of a tissue product is themanufacturing process utilized to create the product. For tissueproducts, there are several manufacturing processes available includingconventional dry crepe, through air drying (TAD), or “hybrid”technologies such as Valmet's NTT and QRT processes, Georgia Pacific'sETAD, and Voith's ATMOS process. Each has differences as to installedcapital cost, raw material utilization, energy cost, production rates,and the ability to generate desired attributes such as softness,strength, and absorbency.

Conventional manufacturing processes include a forming section designedto retain the fiber, chemical, and filler recipe while allowing thewater to drain from the web. Many types of forming sections, such asinclined suction breast roll, twin wire C-wrap, twin wire S-wrap,suction forming roll, and Crescent formers, include the use of formingfabrics.

Forming fabrics are woven structures that utilize monofilaments (such asyarns or threads) composed of synthetic polymers (usually polyethylene,polypropylene, or nylon). A forming fabric has two surfaces, the sheetside and the machine or wear side. The wear side is in contact with theelements that support and move the fabric and are thus prone to wear. Toincrease wear resistance and improve drainage, the wear side of thefabric has larger diameter monofilaments compared to the sheet side. Thesheet side has finer yarns to promote fiber and filler retention on thefabric surface.

Different weave patterns are utilized to control other properties suchas: fabric stability, life potential, drainage, fiber support, andclean-ability. There are three basic types of forming fabrics: singlelayer, double layer, and triple layer. A single layer fabric is composedof one yarn system made up of cross direction (CD) yarns (also known asshute yarns) and machine direction (MD) yarns (also known as warpyarns). The main issue for single layer fabrics is a lack of dimensionalstability. A double layer forming fabric has one layer of warp yarns andtwo layers of shute yarns. This multilayer fabric is generally morestable and resistant to stretching. Triple layer fabrics have twoseparate single layer fabrics bound together by separated yarns calledbinders. Usually the binder fibers are placed in the cross direction butcan also be oriented in the machine direction. Triple layer fabrics havefurther increased dimensional stability, wear potential, drainage, andfiber support than single or double layer fabrics.

The manufacturing of forming fabrics includes the following operations:weaving, initial heat setting, seaming, final heat setting, andfinishing. The fabric is made in a loom using two interlacing sets ofmonofilaments (or threads or yarns). The longitudinal or machinedirection threads are called warp threads and the transverse or machinedirection threads are called shute threads. After weaving, the formingfabric is heated to relieve internal stresses to enhance dimensionalstability of the fabric. The next step in manufacturing is seaming. Thisstep converts the flat woven fabric into an endless forming fabric byjoining the two MD ends of the fabric. After seaming, a final heatsetting is applied to stabilize and relieve the stresses in the seamarea. The final step in the manufacturing process is finishing, wherebythe fabric is cut to width and sealed.

There are several parameters and tools used to characterize theproperties of the forming fabric: mesh and count, caliper, frames, planedifference, open area, air permeability, void volume and distribution,running attitude, fiber support, drainage index, and stacking. None ofthese parameters can be used individually to precisely predict theperformance of a forming fabric on a paper machine, but together theexpected performance and sheet properties can be estimated. Examples offorming fabrics designs can be viewed in U.S. Pat. Nos. 3,143,150,4,184,519, 4,909,284, and 5,806,569.

In a conventional dry crepe process, after web formation and drainage(to around 35% solids) in the forming section (assisted by centripetalforce around the forming roll and, in some cases, vacuum boxes), a webis transferred from the forming fabric to a press fabric upon which theweb is pressed between a rubber or polyurethane covered suction pressureroll and Yankee dryer. The press fabric is a permeable fabric designedto uptake water from the web as it is pressed in the press section, itis composed of large monofilaments or multi-filamentous yarns, needledwith fine synthetic batt fibers to form a smooth surface for even webpressing against the Yankee dryer. Removing water via pressing reducesenergy consumption.

In a conventional TAD process, rather than pressing and compacting theweb, as is performed in conventional dry crepe, the web undergoes thesteps of imprinting and thermal pre-drying. Imprinting is a step in theprocess where the web is transferred from a forming fabric to astructured fabric (or imprinting fabric) and subsequently pulled intothe structured fabric using vacuum (referred to as imprinting ormolding). This step imprints the weave pattern (or knuckle pattern) ofthe structured fabric into the web. This imprinting step increasessoftness of the web, and affects smoothness and the bulk structure. Themanufacturing method of an imprinting fabric is similar to a formingfabric (see U.S. Pat. Nos. 3,473,576, 3,573,164, 3,905,863, 3,974,025,and 4,191,609 for examples) except for an additional step if an overlaidpolymer is utilized.

Imprinting fabrics with an overlaid polymer are disclosed in U.S. Pat.Nos. 5,679,222, 4,514,345, 5,334,289, 4,528,239 and 4,637,859.Specifically, these patents disclose a method of forming a fabric inwhich a patterned resin is applied over a woven substrate. The patternedresin completely penetrates the woven substrate. The top surface of thepatterned resin is flat and openings in the resin have sides that followa linear path as the sides approach and then penetrate the wovenstructure.

U.S. Pat. Nos. 6,610,173, 6,660,362, 6,998,017, and European Patent No.EP 1 339 915 disclose another technique for applying an overlaid resinto a woven imprinting fabric.

After imprinting, the web is thermally pre-dried by moving hot airthrough the web while it is conveyed on the structured fabric. Thermalpre-drying can be used to dry the web to over 90% solids before the webis transferred to a steam heated cylinder. The web is then transferredfrom the structured fabric to the steam heated cylinder though a verylow intensity nip (up to 10 times less than a conventional press nip)between a solid pressure roll and the steam heated cylinder. Theportions of the web that are pressed between the pressure roll and steamcylinder rest on knuckles of the structured fabric; thereby protectingmost of the web from the light compaction that occurs in this nip. Thesteam cylinder and an optional air cap system, for impinging hot air,then dry the sheet to up to 99% solids during the drying stage beforecreping occurs. The creping step of the process again only affects theknuckle sections of the web that are in contact with the steam cylindersurface. Due to only the knuckles of the web being creped, along withthe dominant surface topography being generated by the structuredfabric, and the higher thickness of the TAD web, the creping process hasmuch smaller effect on overall softness as compared to conventional drycrepe. After creping, the web is optionally calendered and reeled into aparent roll and ready for the converting process. Some TAD machinesutilize fabrics (similar to dryer fabrics) to support the sheet from thecrepe blade to the reel drum to aid in sheet stability and productivity.Patents which describe creped through air dried products include U.S.Pat. Nos. 3,994,771, 4,102,737, 4,529,480, and 5,510,002.

The TAD process generally has higher capital costs as compared to aconventional tissue machine due to the amount of air handling equipmentneeded for the TAD section. Also, the TAD process has a higher energyconsumption rate due to the need to burn natural gas or other fuels forthermal pre-drying. However, the bulk softness and absorbency of a paperproduct made from the TAD process is superior to conventional paper dueto the superior bulk generation via structured fabrics, which creates alow density, high void volume web that retains its bulk when wetted. Thesurface smoothness of a TAD web can approach that of a conventionaltissue web. The productivity of a TAD machine is less than that of aconventional tissue machine due to the complexity of the process and thedifficulty of providing a robust and stable coating package on theYankee dryer needed for transfer and creping of a delicate a pre-driedweb.

UCTAD (un-creped through air drying) is a variation of the TAD processin which the sheet is not creped, but rather dried up to 99% solidsusing thermal drying, blown off the structured fabric (using air), andthen optionally calendered and reeled. U.S. Pat. No. 5,607,551 describesan uncreped through air dried product.

A process/method and paper machine system for producing tissue has beendeveloped by the Voith company and is marketed under the name ATMOS. Theprocess/method and paper machine system has several variations, but allinvolve the use of a structured fabric in conjunction with a belt press.The major steps of the ATMOS process and its variations are stockpreparation, forming, imprinting, pressing (using a belt press),creping, calendering (optional), and reeling the web.

The stock preparation step of the ATMOS process is the same as that of aconventional or TAD machine. The forming process can utilize a twin wireformer (as described in U.S. Pat. No. 7,744,726), a Crescent Former witha suction Forming Roll (as described in U.S. Pat. No. 6,821,391), or aCrescent Former (as described in U.S. Pat. No. 7,387,706). The former isprovided with a slurry from the headbox to a nip formed by a structuredfabric (inner position/in contact with the forming roll) and formingfabric (outer position). The fibers from the slurry are predominatelycollected in the valleys (or pockets, pillows) of the structured fabricand the web is dewatered through the forming fabric. This method forforming the web results in a bulk structure and surface topography asdescribed in U.S. Pat. No. 7,387,706 (FIGS. 1-11). After the formingroll, the structured and forming fabrics separate, with the webremaining in contact with the structured fabric.

The web is now transported on the structured fabric to a belt press. Thebelt press can have multiple configurations. The press dewaters the webwhile protecting the areas of the sheet within the structured fabricvalleys from compaction. Moisture is pressed out of the web, through thedewatering fabric, and into the vacuum roll. The press belt is permeableand allows for air to pass through the belt, web, and dewatering fabric,and into the vacuum roll, thereby enhancing the moisture removal. Sinceboth the belt and dewatering fabric are permeable, a hot air hood can beplaced inside of the belt press to further enhance moisture removal.Alternately, the belt press can have a pressing device which includesseveral press shoes, with individual actuators to control crossdirection moisture profile, or a press roll. A common arrangement of thebelt press has the web pressed against a permeable dewatering fabricacross a vacuum roll by a permeable extended nip belt press. Inside thebelt press is a hot air hood that includes a steam shower to enhancemoisture removal. The hot air hood apparatus over the belt press can bemade more energy efficient by reusing a portion of heated exhaust airfrom the Yankee air cap or recirculating a portion of the exhaust airfrom the hot air apparatus itself.

After the belt press, a second press is used to nip the web between thestructured fabric and dewatering felt by one hard and one soft roll. Thepress roll under the dewatering fabric can be supplied with vacuum tofurther assist water removal. This belt press arrangement is describedin U.S. Pat. Nos. 8,382,956 and 8,580,083, with FIG. 1 showing thearrangement. Rather than sending the web through a second press afterthe belt press, the web can travel through a boost dryer, a highpressure through air dryer, a two pass high pressure through air dryeror a vacuum box with hot air supply hood. U.S. Pat. Nos. 7,510,631,7,686,923, 7,931,781, 8,075,739, and 8,092,652 further describe methodsand systems for using a belt press and structured fabric to make tissueproducts each having variations in fabric designs, nip pressures, dwelltimes, etc., and are mentioned here for reference. A wire turning rollcan be also be utilized with vacuum before the sheet is transferred to asteam heated cylinder via a pressure roll nip.

The sheet is now transferred to a steam heated cylinder via a presselement. The press element can be a through drilled (bored) pressureroll, a through drilled (bored) and blind drilled (blind bored) pressureroll, or a shoe press. After the web leaves this press element andbefore it contacts the steam heated cylinder, the % solids are in therange of 40-50%. The steam heated cylinder is coated with chemistry toaid in sticking the sheet to the cylinder at the press element nip andalso to aid in removal of the sheet at the doctor blade. The sheet isdried to up to 99% solids by the steam heated cylinder and an installedhot air impingement hood over the cylinder. This drying process, thecoating of the cylinder with chemistry, and the removal of the web withdoctoring is explained in U.S. Pat. Nos. 7,582,187 and 7,905,989. Thedoctoring of the sheet off the Yankee, i.e., creping, is similar to thatof TAD with only the knuckle sections of the web being creped. Thus, thedominant surface topography is generated by the structured fabric, withthe creping process having a much smaller effect on overall softness ascompared to conventional dry crepe. The web is now calendered(optional), slit, reeled and ready for the converting process.

The ATMOS process has capital costs between that of a conventionaltissue machine and a TAD machine. It uses more fabrics and a morecomplex drying system compared to a conventional machine, but uses lessequipment than a TAD machine. The energy costs are also between that ofa conventional and a TAD machine due to the energy efficient hot airhood and belt press. The productivity of the ATMOS machine has beenlimited due to the inability of the novel belt press and hood to fullydewater the web and poor web transfer to the Yankee dryer, likely drivenby poor supported coating packages, the inability of the process toutilize structured fabric release chemistry, and the inability toutilize overlaid fabrics to increase web contact area to the dryer. Pooradhesion of the web to the Yankee dryer has resulted in poor creping andstretch development which contributes to sheet handling issues in thereel section. The result is that the output of an ATMOS machine iscurrently below that of conventional and TAD machines. The bulk softnessand absorbency is superior to conventional, but lower than a TAD websince some compaction of the sheet occurs within the belt press,especially areas of the web not protected within the pockets of thefabric. Also, bulk is limited since there is no speed differential tohelp drive the web into the structured fabric as exists on a TADmachine. The surface smoothness of an ATMOS web is between that of a TADweb and a conventional web primarily due to the current limitation onuse of overlaid structured fabrics.

The ATMOS manufacturing technique is often described as a hybridtechnology because it utilizes a structured fabric like the TAD process,but also utilizes energy efficient means to dewater the sheet like theconventional dry crepe process. Other manufacturing techniques whichemploy the use of a structured fabric along with an energy efficientdewatering process are the ETAD process and NTT process. The ETADprocess and products are described in U.S. Pat. Nos. 7,339,378,7,442,278, and 7,494,563. The NTT process and products are described inWO 2009/061079 A1, US Patent Application Publication No. 2011/0180223A1, and US Patent Application Publication No. 2010/0065234 A1. The QRTprocess is described in US Patent Application Publication No.2008/0156450 A1 and U.S. Pat. No. 7,811,418. A structuring beltmanufacturing process used for the NTT, QRT, and ETAD imprinting processis described in U.S. Pat. No. 8,980,062 and U.S. Patent ApplicationPublication No. US 2010/0236034.

The NIT process involves spirally winding strips of polymeric material,such as industrial strapping or ribbon material, and adjoining the sidesof the strips of material using ultrasonic, infrared, or laser weldingtechniques to produce an endless belt. Optionally, a filler or gapmaterial can be placed between the strips of material and melted usingthe aforementioned welding techniques to join the strips of materials.The strips of polymeric material are produced by an extrusion processfrom any polymeric resin such as polyester, polyamide, polyurethane,polypropylene, or polyether ether ketone resins. The strip material canalso be reinforced by incorporating monofilaments of polymeric materialinto the strips during the extrusion process or by laminating a layer ofwoven polymer monofilaments to the non-sheet contacting surface of afinished endless belt composed of welded strip material. The endlessbelt can have a textured surface produced using processes such assanding, graving, embossing, or etching. The belt can be impermeable toair and water, or made permeable by processes such as punching,drilling, or laser drilling. Examples of structuring belts used in theNIT process can be viewed in International Publication Number WO2009/067079 A1 and US Patent Application Publication No. 2010/0065234A1.

As shown in the aforementioned discussion of tissue papermakingtechnologies, the fabrics or belts utilized are critical in thedevelopment of the tissue web structure and topography which, in turn,are instrumental in determining the quality characteristics of the websuch as softness (bulk softness and surfaces smoothness) and absorbency.The manufacturing process for making these fabrics has been limited toweaving a fabric (primarily forming fabrics and structured fabrics) or abase structure and needling synthetic fibers (press fabrics) oroverlaying a polymeric resin (overlaid structured fabrics) to thefabric/base structure, or welding strips of polymeric material togetherto form an endless belt.

Conventional overlaid structures require application of an uncuredpolymer resin over a woven substrate where the resin completelypenetrates through the thickness of the woven stricture. Certain areasof the resin are cured and other areas are uncured and washed away fromthe woven structure. This results is a fabric where airflow through thefabric is only possible in the Z-direction. Thus, in order for the webto dry efficiently, only highly permeable fabrics can be utilized,meaning the amount of overlaid resin applied needs to be limited. If afabric of low permeability is produced in this manner, then dryingefficiency is significantly reduced, resulting in poor energy efficiencyand/or low production rates as the web must be transported slowly acrossthe TAD drums or ATMOS drum for sufficient drying. Similarly, a weldedpolymer structuring layer is extremely planar and provides an evensurface when laminating to a woven support layer (FIG. 9), which resultsin little if any air channels in the X-Y plane.

SUMMARY OF THE INVENTION

An object of this invention is to provide an alternate process formanufacturing structured fabrics. It is also the purpose of thisinvention to provide a less complex, lower cost, higher productiontechnique to produce these fabrics. This process can be used to producestructuring fabrics and forming fabrics.

In an exemplary embodiment, the inventive process uses extrudedpolymeric netting material to create the fabric. The extruded polymernetting is optionally laminated to additional layers of extruded polymernetting, woven polymer monofilament, or woven monofilaments ormulti-filamentous yarns needled with fine synthetic batt fibers.

Another object of this invention is to provide a press section of apaper machine that can utilize the inventive structuring fabric toproduce high quality, high bulk tissue paper. This press sectioncombines the low capital cost, high production rate, low energyconsumption advantages of the NTT manufacturing process, but improvesthe quality to levels that can be achieved with TAD technology.

The inventive process avoids the tedious and expensive conventionalprior art process used to produce woven fabrics using a loom or thetime, cost, and precision needed to produce welded fabrics using wovenstrips of polymeric material that need to be engraved, embossed, orlaser drilled. The fabrics produced using the inventive process can beutilized as forming fabrics on any papermaking machine or as astructuring belt on tissue machines utilizing the TAD (creped oruncreped), NTT, QRT, ATMOS, ETAD or other hybrid processes.

In an exemplary embodiment, a low porosity structuring belt of theinventive design is used on a TAD machine where the air flows throughthe TAD drum from a hot air impingement hood or air cap. High air flowthrough the inventive structuring belt is not required to effectivelydry the imprinted sheet, leading to lower heat demand and fuelconsumption.

In an exemplary embodiment, a press section of a tissue machine can beused in conjunction with structured fabrics of this invention to producehigh quality tissue with low capital and operational costs. Thiscombination of high quality tissue produced at high productivity ratesusing low capital and operational costs is not currently available usingconventional technologies.

According to an exemplary embodiment of the present invention, a fabricor belt for a papermaking machine comprises: a first layer that definesa web contacting surface, the first layer being made of extruded polymerand comprising: a plurality of first elements aligned in a firstdirection; a plurality of second elements aligned in a second directionand extending over the plurality of first elements; and a plurality ofopen portions defined by the plurality of first and second elements; anda second layer made of woven fabric that supports the first layer,wherein the first layer is bonded to the second layer so that the firstlayer extends only partially through the second layer and an interfaceformed between the first and second layers comprises airflow channelsthat extend in a plane parallel to the first and second layers.

According to at least one exemplary embodiment, the interface betweenthe first and second layers comprises bonded and non-bonded portions.

According to at least one exemplary embodiment, the first layer extendsinto the second layer by an amount of 30 μm or less.

According to at least one exemplary embodiment, the first layer has athickness of 0.25 mm to 1.7 mm.

According to at least one exemplary embodiment, the first layer has athickness of 0.4 mm to 0.75 mm.

According to at least one exemplary embodiment, the first layer has athickness of 0.5 mm to 0.6 mm.

According to at least one exemplary embodiment, the plurality of openportions repeat across the first layer in both machine and crossdirections at regular intervals.

According to at least one exemplary embodiment, the plurality of openportions are rectangular-shaped open portions.

According to at least one exemplary embodiment, the rectangular-shapedopen portions are defined by sides with a length of 0.25 mm to 1.0 mm.

According to at least one exemplary embodiment, the rectangular-shapedopen portions are defined by sides with a length of 0.4 mm to 0.75 mm.

According to at least one exemplary embodiment, the rectangular-shapedopen portions are defined by sides with a length of 0.5 mm to 0.7 mm.

According to at least one exemplary embodiment, the plurality of openportions are square-shaped open portions.

According to at least one exemplary embodiment, the plurality of openportions are circular-shaped open portions.

According to at least one exemplary embodiment, the diameter of thecircular-shaped open portions is 0.25 mm to 1.0 mm.

According to at least one exemplary embodiment, the diameter of thecircular-shaped open portions is 0.4 mm to 0.75 mm.

According to at least one exemplary embodiment, the diameter of thecircular-shaped open portions is 0.1 mm to 0.7 mm.

According to at least one exemplary embodiment, the plurality of secondelements extend above the plurality of first elements by an amount of0.05 mm to 0.4 mm.

According to at least one exemplary embodiment, the plurality of secondelements extend above the plurality of first elements by an amount of0.1 mm to 0.3 mm.

According to at least one exemplary embodiment, the plurality of secondelements extend above the plurality of first elements by an amount of0.1 mm to 0.2 mm.

According to at least one exemplary embodiment, the plurality of secondelements have a width of 0.1 mm to 0.5 mm.

According to at least one exemplary embodiment, the plurality of secondelements have a width of 0.2 mm to 0.4 mm.

According to at least one exemplary embodiment, the plurality of secondelements have a width of 0.25 mm to 0.3 mm.

According to at least one exemplary embodiment, the plurality of firstelements have a thickness of 0.15 mm to 0.75 mm.

According to at least one exemplary embodiment, the plurality of firstelements have a thickness of 0.3 mm to 0.6 mm.

According to at least one exemplary embodiment, the plurality of firstelements have a thickness of 0.4 mm to 0.6 mm.

According to at least one exemplary embodiment, the plurality of firstelements have a width of 0.25 mm to 1.0 mm.

According to at least one exemplary embodiment, the plurality of firstelements have a width of 0.3 mm to 0.5 mm.

According to at least one exemplary embodiment, the plurality of firstelements have a width of 0.4 mm to 0.5 mm.

According to at least one exemplary embodiment, the first layer is madeof polymer or copolymer.

According to at least one exemplary embodiment, the first layer is madeof an extruded netting tube.

According to at least one exemplary embodiment, the extruded nettingtube is stretched to orient the polymer or copolymer.

According to at least one exemplary embodiment, the first layer is madeof a perforated sheet.

According to at least one exemplary embodiment, the perforated sheet isstretched to orient the polymer or copolymer.

According to at least one exemplary embodiment, the perforated sheet isseamed using thermal, laser, infrared or ultraviolet seaming.

According to at least one exemplary embodiment, the second layercomprises woven polymeric monofilaments.

According to at least one exemplary embodiment, the second layercomprises woven monofilaments or multi-filamentous yarns needled withfine synthetic batt fibers.

According to at least one exemplary embodiment, the second layer has a 5shed weave with a non-numerical warp pick sequence.

According to at least one exemplary embodiment, the second layer has amesh of 10 to 30 frames/cm.

According to at least one exemplary embodiment, the second layer has amesh of 15 to 25 frames/cm.

According to at least one exemplary embodiment, the second layer has amesh of 17 to 22 frames/cm.

According to at least one exemplary embodiment, the second layer has acount of 5 to 30 frames/cm.

According to at least one exemplary embodiment, the second layer has acount of 10 to 20 frames/cm.

According to at least one exemplary embodiment, the second layer has acount of 15 to 20 frames/cm.

According to at least one exemplary embodiment, the second layer has acaliper of 0.5 mm to 1.5 mm.

According to at least one exemplary embodiment, the second layer has acaliper of 0.5 mm to 1.0 mm.

According to at least one exemplary embodiment, the second layer has acaliper of 0.5 mm to 0.75 mm.

According to at least one exemplary embodiment, the second layer isbonded to the first layer by thermal, ultrasonic, ultraviolet orinfrared welding.

According to at least one exemplary embodiment, the second layer isbonded to the first layer with a 20% to 50% contact area.

According to at least one exemplary embodiment, the second layer isbonded to the first layer with a 20% to 30% contact area.

According to at least one exemplary embodiment, the second layer isbonded to the first layer with a 25% to 30% contact area.

According to at least one exemplary embodiment, the fabric or belt hasan air permeability of 20 cfm to 300 cfm.

According to at least one exemplary embodiment, the fabric or belt hasan air permeability of 100 cfm to 250 cfm.

According to at least one exemplary embodiment, the fabric or belt hasan air permeability of 200 cfm to 250 cfm.

According to at least one exemplary embodiment, the fabric or belt is astructuring fabric configured for use on a papermaking machine.

According to at least one exemplary embodiment, the papermaking machineis a Through Air Dried, ATMOS, NTT, QRT or ETAD tissue making machine.

According to at least one exemplary embodiment, the fabric or belt is aforming fabric configured for use on a papermaking machine.

According to at least one exemplary embodiment, the plurality of secondelements extend below the plurality of first elements.

According to at least one exemplary embodiment, the plurality of secondelements extend below the plurality of first elements by less than 0.40mm.

According to at least one exemplary embodiment, the plurality of secondelements extend below the plurality of first elements by 0.1 mm to 0.3mm.

According to at least one exemplary embodiment, the plurality of secondelements extend below the plurality of first elements by 0.1 mm to 0.2mm.

According to at least one exemplary embodiment, the first direction issubstantially parallel to a machine cross direction.

According to at least one exemplary embodiment, the second direction issubstantially parallel to a machine direction.

According to at least one exemplary embodiment, the first direction issubstantially parallel to a machine direction.

According to at least one exemplary embodiment, the second direction issubstantially parallel to a machine cross direction.

A fabric or belt for a papermaking machine according to an exemplaryembodiment of the present invention comprises: a first layer thatdefines a web contacting surface, the first layer being made of extrudedpolymer and comprising: a plurality of first elements aligned in a firstdirection; a plurality of second elements aligned in a second directionand extending over the plurality of first elements; and a plurality ofopen portions defined by the plurality of first and second elements; anda second layer made of woven fabric that supports the first layer,wherein the first layer is bonded to the second layer so as to form aninterface between the first and second layers that comprises bonded andunbonded portions and airflow channels that extend in a plane parallelto the first and second layers.

According to at least one exemplary embodiment, the first layer extendsonly partially through the second layer.

According to at least one exemplary embodiment, the first layer extendsinto the second layer by an amount of 30 μm or less.

A fabric or belt for a papermaking machine according to an exemplaryembodiment of the present invention comprises: a first layer hat definesa web contacting surface, the first layer comprising a plurality ofgrooves aligned substantially in the machine direction; and a secondlayer made of woven fabric that supports the first layer, wherein thefirst layer is bonded to the second layer so as to form an interfacebetween the first and second layers that comprises bonded and unbondedportions and airflow channels that extend in a plane parallel to thefirst and second layers.

According to at least one exemplary embodiment, the plurality of groovesare angled 0.1% to 45% relative to the machine direction.

According to at least one exemplary embodiment, the plurality of groovesare angled 0.1% to 5% relative to the machine direction.

According to at least one exemplary embodiment, the plurality of groovesare angled 2% to 3% relative to the machine direction.

According to at least one exemplary embodiment, the plurality of grooveshave a depth of 0.25 mm to 1.0 mm.

According to at least one exemplary embodiment, the plurality of grooveshave a depth of 0.4 mm to 0.75 mm.

According to at least one exemplary embodiment, the plurality of grooveshave a depth of 0.4 mm to 0.6 mm.

According to at least one exemplary embodiment, the plurality of grooveshave a square, semicircular or tapered cross section.

According to at least one exemplary embodiment, the plurality of groovesare spaced 0.1 mm to 1.5 mm apart from each other.

According to at least one exemplary embodiment, the plurality of groovesare spaced 0.2 mm to 0.5 mm apart from each other.

According to at least one exemplary embodiment, the plurality of groovesare spaced 0.2 mm to 0.3 mm apart from ach other.

According to at least one exemplary embodiment, the plurality of groovesare formed by laser drilling.

According to at least one exemplary embodiment, the fabric or belt issubjected to punching, drilling or laser drilling to achieve an airpermeability of 20 cfm to 200 cfm.

According to at least one exemplary embodiment, the fabric or belt hasan air permeability of 20 cfm to 100 cfm.

According to at least one exemplary embodiment, the fabric or belt hasan air permeability of 10 cfm to 50 cfm.

A fabric or belt for a papermaking machine according to an exemplaryembodiment of the present invention comprises: first layer that definesa web contacting surface, the first layer comprising: a plurality offirst elements aligned in a cross direction, the plurality of firstelements having a thickness of 0.3 mm to 0.6 mm and a width of 0.4 mm to0.5 mm; a plurality of second elements aligned in a machine directionand extending over the plurality of first elements by an amount of 0.1mm to 0.2 mm and having a width of 0.25 mm to 0.3 mm; and a plurality ofopen portions defined by the plurality of first and second elements andthat repeat across the at least one nonwoven layer in both the machineand cross directions at regular intervals, the plurality of openportions being square shaped and defined by sides with a length of 0.5mm to 0.7 mm; and a woven fabric layer that supports the at least onelayer, wherein the fabric or belt has an air permeability of 20 cfm to300 cfm.

A fabric or belt for a papermaking machine according to an exemplaryembodiment of the present invention comprises: at least one layer thatdefines a web contacting surface, the at least one layer comprising: aplurality of first elements aligned in a cross direction, the pluralityof first elements having a thickness of 0.3 mm to 0.6 mm and a width of0.4 mm to 0.5 mm; a plurality of second elements aligned in a machinedirection and extending over the plurality of first elements by anamount of 0.1 mm to 0.2 mm and having a width of 0.25 mm to 0.3 mm; anda plurality of open portions defined by the plurality of first andsecond elements and that repeat across the at least one layer in boththe machine and cross directions at regular intervals, the plurality ofopen portions being circular shaped with a diameter of 0.5 mm to 0.7 mm;and a woven fabric layer that supports the at least one layer, whereinthe fabric or belt has an air permeability of 20 cfm to 300 cfm.

A method of forming a tissue product according to an exemplaryembodiment of the present invention comprises: depositing a nascentpaper web onto a forming fabric of a papermaking machine so as to form apaper web; at least partially dewatering the paper web through astructuring fabric of a press section of the papermaking machine,wherein the structuring fabric comprises: a first layer that defines aweb contacting surface, the first layer being made of extruded polymerand comprising: a plurality of first elements aligned in a firstdirection; a plurality of second elements aligned in a second directionand extending over the plurality of first elements; and a plurality ofopen portions defined by the plurality of first and second elements; anda second layer made of woven fabric that supports the first layer,wherein the first layer is bonded to the second layer so that the firstlayer extends only partially through the second layer and an interfaceformed between the first and second layers comprise airflow channelsthat extend in a plane parallel to the first and second layers; anddrying the at least partially dewatered paper web at a drying section ofthe papermaking machine.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and advantages of exemplary embodiments of the presentinvention will be more fully understood with reference to the following,detailed description when taken in conjunction with the accompanyingfigures, wherein:

FIG. 1 is a cross-sectional view of a fabric or belt according to anexemplary embodiment of the present invention;

FIG. 2 is a top planar view of the fabric or belt of FIG. 1;

FIG. 3 is a block diagram of a press section according to an exemplaryembodiment of the present invention;

FIG. 4 is a cross-sectional view of a fabric or belt according to anexemplary embodiment of the present invention;

FIG. 5 is a planar view of the fabric of belt of FIG. 4;

FIG. 6 is a photo showing a magnified image of a fabric or beltaccording to an exemplary embodiment of the present invention;

FIG. 7 is a photo of a fabric or belt according to an exemplaryembodiment of the present invention;

FIG. 8 is a photo showing air channels formed in the fabric or beltaccording to an exemplary embodiment of the present invention;

FIG. 9 is a photo of a welded polymer structuring layer according to theconventional art;

FIG. 10 is a cross-sectional view of a fabric or belt according to anexemplary embodiment of the present invention;

FIG. 11 is a cross-sectional view of a fabric or belt according to anexemplary embodiment of the present invention; and

FIG. 12 is a sectional perspective view of a fabric or belt according toan exemplary embodiment of the present invention.

DETAILED DESCRIPTION

Current methods for manufacturing papermaking fabrics are very timeconsuming and expensive, requiring weaving together polymermonofilaments using a loom and optionally binding a polymer overlay, orbinding strips of polymeric ribbon material together using ultrasonic,infrared, or ultraviolet welding techniques. According to an exemplaryembodiment of the present invention, a layer of extruded polymericmaterial is formed separately from a woven fabric layer, and the layerof polymeric material is attached to the woven fabric layer to form thefabric or belt structure. The layer of polymeric material includeselevated elements that extend substantially in the machine direction orcross direction.

In an exemplary embodiment, the layer of polymeric material is extrudedpolymer netting. Extruded netting tubes were first manufactured around1956 in accordance with the process described in U.S. Pat. No.2,919,467. The process creates a polymer net which in general hasdiamond shaped openings extending along the length of the tube. Sincethis process was pioneered, it has grown tremendously, with extrudedsquare netting tubes being described in U.S. Pat. Nos. 3,252,181,3,384,692, and 4,038,008. Nets can also be extruded in flat sheets asdescribed in U.S. Pat. No. 3,666,609 which are then perforated orembossed to a selected geometric configuration. Heating and stretchingthe netting is conducted to enlarge the openings in the net structureand orient the polymers to increase strength. Tube netting can bestretched over a cylindrical mandrel while both tube and flat sheetnetting can be stretched in the longitudinal and transverse directionsusing several techniques. U.S. Pat. No. 4,190,692 describes a process ofstretching the netting to orient the polymer and increase strength.

Today, various types of polymers can be extruded to provide the optimallevel of strength, stretch, heat resistance, abrasion resistance and avariety of other physical properties. Polymers can be coextruded inlayers allowing for an adhesive agent to be incorporated into the outershell of the netting to facilitate thermal lamination of multiple layersof netting.

According to an exemplary embodiment of the present invention, extrudednetted tubes are used in fabrics in the papermaking process to lower thematerial cost, improve productivity, and improve product quality. Thepositions where this type of fabric can have the most impact are as theforming fabrics of any paper machine or as the structuring fabric onThrough Air Dried (creped or uncreped), ATMOS, NTT, QRT or ETAD tissuepaper making machines.

The extruded netted tubes have openings that are square, diamond,circular, or any geometric shape that can be produced with the dyeequipment used in the extrusion process. The netted tubes are composedof any combination of polymers necessary to develop the stretch,strength, heat resistance, and abrasion resistance necessary for theapplication. Additionally, coextrusion is preferred with an adhesiveagent incorporated into the outer shell of the netting. The adhesiveagent facilitates thermal lamination of multiple layers of netting,thermal lamination of netting to woven monofilaments, or thermallamination of netting to woven monofilaments or multi-filamentous yarnsneedled with fine synthetic batt fibers. The netting is preferablystretched across a cylindrical mandrel to orient the polymers forincreased strength and control over the size of the openings in thenetting.

Netting that has been extruded in flat sheets and perforated withopenings in the preferred geometric shapes can also be utilized. Thesenettings are preferably coextruded with an adhesive agent incorporatedinto the outer shell of the netting to facilitate thermal lamination ofmultiple layers of netting, thermal lamination of netting to wovenmonofilaments, or thermal lamination of netting to woven monofilamentsor multi-filamentous yarns needled with fine synthetic batt fibers. Thenetting is preferable heated and stretched in the longitudinal andtransverse direction to control the size of the opening and increasestrength of the net. When flat netting is utilized, seaming is used toproduce an endless tribe. Seaming techniques using a laser or ultrasonicwelding are preferred.

FIG. 1 is a cross-sectional view and FIG. 2 is a top planar view of astructuring belt or fabric, generally designated by reference number 1,according to an exemplary embodiment of the present invention. The beltor fabric 1 is multilayered and includes a layer 2 that forms the sideof the belt or fabric carrying the paper web, and a woven fabric layer 4forming the non-paper web contacting side of the belt or fabric. Thelayer 2 is comprised of netted tube of coextruded polymer with athickness (T1) of 0.25 mm to 1.7 mm, with openings being regularlyrecurrent and distributed in the longitudinal (MD) and cross direction(CD) of the layer 2 or substantially parallel (plus or minus 10 degrees)thereto. The openings are square with a width (W1) and length (L1)between 0.25 to 1.0 mm or circular with a diameter between 0.25 to 1.0mm. The MD aligned elements of the netting of the layer 2 extend (E1)0.05 to 0.40 mm above the top plane of the CD aligned elements of thenetting. The CD aligned elements of the netting of the structuring layer2 have a thickness (T2) of 0.34 mm. The widths (W3) of the MD alignedelements of the netting of the layer 2 are between 0.1 to 0.5 mm. Thewidths (W2) of the CD aligned elements are between 0.25 to 1.0 mm, aswell. The two layers 2, 4 are laminated together using heat to melt theadhesive in the polymer of the layer 2. Ultrasonic, infrared, and laserwelding can also be utilized to laminate the layers 2, 4. As discussedin further detail below, the lamination of the two layers results in thelayer 2 extending only partially through the thickness of the wovenfabric layer 4, with some portions of the layer 2 remaining unbonded tothe woven fabric layer 4.

Optionally, as shown in FIG. 10, the MD aligned elements of the nettingof the layer 1 can extend (E2) up to 0.40 mm below the bottom plane ofthe CD aligned portion of the netting to further aid in air flow in theX-Y plane of the fabric or belt and supported web. In other embodiments,the elements described above as being MD and CD aligned elements may bealigned to the opposite axis or aligned off axis from the MD and/or CDdirections.

The woven fabric layer 4 is comprised of a woven polymeric fabric with apreferred mesh of between 10-30 frames/cm, a count of 5 to 30 frames/cm,and a caliper from 0.5 mm to 1.5 mm. This layer preferably has a fiveshed non numerical consecutive warp-pick sequence (as described in U.S.Pat. No. 4,191,609) that is sanded to provide 20 to 50 percent contactarea with the layer 2. The fabric or belt 1 with a woven fabric layer 4of this design is suitable on any TAD or ATMOS asset. Optionally, thewoven fabric layer 4 is composed of woven monofilaments ormulti-filamentous yarns needled with fine synthetic batt fibers similarstandard press fabric used in the conventional tissue papermaking presssection. The fabric or belt 1 with a woven fabric layer 4 of this designis suitable on any NTT, QRT, or ETAD machine.

FIGS. 6-8 are photographs, FIG. 11 is a cross-sectional view and FIG. 12is a perspective view of a belt or fabric, generally designated byreference number 300, according to an exemplary embodiment of thepresent invention. The belt or fabric 300 is produced by laminating analready cured polymer netted layer 318 to a woven fabric layer 310. Thepolymer netted layer 318 includes CD aligned elements 314 and MD alignedelements 312. The CD aligned elements 314 and the MD aligned elements312 cross one another with spaces between adjacent elements so as toform openings. As best shown in the photographs of FIGS. 6-8, both theextruded polymer netting layer 318 and woven layer 310 have non-planar,irregularly shaped surfaces that when laminated together only bondtogether where the two layers come into direct contact. The laminationresults in the extruded polymer layer 318 extending only partially intothe woven layer 310 so that any bonding that takes place between the twolayers occurs at or near the surface of the woven layer 310. In apreferred embodiment, the extruded polymer layer 318 extends into thewoven layer 310 to a depth of 30 microns or less. As shown in FIG. 11,the partial and uneven bonding between the two layers results information of air channels 320 that extend in the X-Y plane of the fabricor belt 300. This in turn allows air to travel in the X-Y plane along asheet (as well as within the fabric or belt 300) being held by thefabric or belt 300 during TAD, UCTAD, or ATMOS processes. Without beingbound by theory, it is believed that the fabric or belt 300 removeshigher amounts of water due to the longer airflow path and dwell time ascompared to conventional designs. In particular, previously known wovenand overlaid fabric designs create channels where airflow is restrictedin movement in regards to the X-Y direction and channeled in theZ-direction by the physical restrictions imposed by pockets formed bythe monofilaments or polymers of the belt. The inventive design allowsfor airflow in the X-Y direction, such that air can move parallelthrough the belt and web across multiple pocket boundaries and increasecontact time of the airflow within the web to remove additional water.This allows the use of belts with lower permeability compared toconventional fabrics without increasing the energy demand per ton ofpaper dried. The air flow in the X-Y plane also reduces high velocityair flow in the Z-direction as the sheet and fabric pass across themolding box, thereby reducing the formation of pin holes in the sheet.

In an exemplary embodiment, the woven layer 310 is composed ofpolyethylene terephthalate (PET), Conventional non-overlaid structuringfabrics made of PET typically have a failure mode in which fibrillationof the sheet side of the monofilaments occurs due to high pressure fromcleaning showers, compression at the pressure roll nip, and heat fromthe TAD, UCTAD, or ATMOS module. The non-sheet side typicallyexperiences some mild wear and loss of caliper due to abrasion acrossthe paper machine rolls and is rarely the cause of fabric failure. Bycontrast, the extruded polymer layer 318 is composed of polyurethane,which has higher impact resistance as compared to PET to better resistdamage by high pressure showers. It also has higher load capacity inboth tension and compression such that it can undergo a change in shapeunder a heavy load but return to its original shape once the load isremoved (which occurs in the pressure roll nip). Polyurethane also hasexcellent flex fatigue resistance, tensile strength, tear strength,abrasion resistance, and heat resistance. These properties allow thefabric to be durable and run longer on the paper machine than a standardwoven fabric. Additionally the woven structure can be sanded to increasethe surface area that contacts the extruded polymer layer to increasethe total bonded area between the two layers. Varying the degree ofsanding of the woven structure can alter the bonded area from 10% to upto 50% of the total surface area of the woven fabric that lies beneaththe extruded polymer layer. The preferred bonded area is approximately20-30% which provides sufficient durability to the fabric withoutclosing excessive amounts of air channels in the X-Y plane of thefabric, which in turn maintains improved drying efficiency compared toconventional fabrics.

FIG. 3 shows a press section according to an exemplary embodiment of thepresent invention. The press section is similar to the press sectiondescribed in US Patent Application Publication No. 2011/0180223 exceptthe press is comprised of suction pressure roll 14 and an extended nipor shoe press 13. A paper web, supported upon a press fabric 10 composedof woven monofilaments or multi-filamentous yarns needled with finesynthetic batt fibers, is transported through this press section nip andtransferred to the structuring belt 12. The structuring belt 12 iscomprised of a structuring layer of extruded netting welded polymericstrips made permeable with holes formed by laser drilling (or othersuitable mechanical processes) and laminated to a support layercomprised of woven monofilaments or multi-filamentous yarns needled withfine synthetic batt fibers. The support layer is preferably comprised ofa material typical of a press fabric used on a conventional tissuemachine. The paper web is dewatered through both sides of the sheet intothe press fabric 10 and structuring fabric 12 as the web passes throughthe nip of the press section. The suction pressure roll 14 is preferablya through drilled, blind drilled, and/or grooved polyurethane coveredroll.

This press section improves the softness, bulk, and absorbency of webcompared to the NTT process. The NTT process flattens the web inside thepocket of the fabric since all the force is being applied by the shoepress to push the web into a fabric pocket that is impermeable or ofextremely low permeability to build up hydraulic force to remove thewater. The inventive press section uses a press to push the web into apermeable fabric pocket while also drawing the sheet into the fabricpocket using vacuum. This reduces the necessary loading force needed bythe shoe press and reduces the buildup of hydraulic pressure, both ofwhich would compress the sheet. The result is that the web within thefabric pocket remains thicker and less compressed, giving the webincreased bulk, increased void volume and absorbency, and increased bulksoftness. The press section still retains the simplicity, high speedoperation, and low energy cost platform of the NTT, but improves thequality of the product.

FIG. 4 is a cross-sectional view and FIG. 5 is a top planar view of astructuring belt or fabric, generally designated by reference number100, according to another exemplary embodiment of the present invention.The belt or fabric 100 is multilayered and includes a layer 102 thatforms the side of the belt or fabric carrying the paper web, and a wovenfabric layer 104 forming the non-paper web contacting side of the beltor fabric. The layer 102 is made of a polymeric material and, in anexemplary embodiment, the layer 102 is made of a sheet of extrudedpolymeric material. Grooves 103 are formed in the layer 102 (forexample, by laser drilling) that extend at an angle (A) relative to themachine direction, and in embodiments the grooves 103 are angled 0.1% to45% relative to the machine direction, preferably 0.1% to 5% relative tothe machine direction, and more preferably 2% to 3% relative to themachine direction. The grooves 103 have a depth (D) of 0.25 mm to 1.0mm, preferably 0.4 mm to 0.75 mm, and more preferably 0.4 mm to 0.6 mm.The grooves 103 have a square, semicircular or tapered profile, and arespaced 0.1 mm to 1.5 mm apart (S), preferably 0.2 mm to 0.5 mm apart,and more preferably 0.2 mm to 0.3 mm apart. The layer 102 has athickness (T4) of 0.25 mm to 1.5 mm, preferably 0.5 mm to 1.0 mm, andmore preferably 0.75 mm to 1.0 mm. The fabric or belt 100 is subjectedto punching, drilling or laser drilling to achieve an air permeabilityof 20 cfm to 200 cfm, preferably 20 cfm to 100 cfm, and more preferably10 cfm to 50 cfm.

In a variation of the exemplary embodiment shown in FIG. 4, additionalgrooves are formed in the layer 102 which extend in the cross direction.Portions of the layer 102 between the cross direction grooves are lowerthan portions between the machine direction grooves, so that theportions between the machine direction grooves form elevated elements inthe surface of the layer 102 in contact with the web, similar to theembodiment shown in FIG. 1.

The following example and test results demonstrate e advantages of thepresent invention.

Softness Testing

Softness of a 1-ply tissue web was determined using a Tissue SoftnessAnalyzer (TSA), available from EMTECH Electronic GmbH of Leipzig,Germany. A punch was used to cut out three 100 cm² round samples fromthe web. One of the samples was loaded into the TSA, clamped into place,and the Tissue Basesheet II algorithm was selected from the list ofavailable softness testing algorithms displayed by the TSA. Afterinputting parameters for the sample, the TSA measurement program wasrun. The test process was repeated for the remaining samples and theresults for all the samples were averaged.

Stretch & MD, CD, and Wet CD Tensile Strength Testing

An Instron 3343 tensile tester, manufactured by Instron of Norwood,Mass., with a 100N load cell and 25.4 mm rubber coated jaw faces wasused for tensile strength measurement. Prior to measurement, the Instron3343 tensile tester was calibrated. After calibration, 8 strips of 1-plyproduct, each one inch by four inches, were provided as samples for eachtest. The strips were cut in the MD direction when testing MD and in theCD direction when testing CD. One of the sample strips was placed inbetween the upper jaw faces and clamp, and then between the lower jawfaces and clamp with a gap of 2 inches between the clamps. A test wasrun on the sample strip to obtain tensile and stretch. The testprocedure was repeated until all the samples were tested. The valuesobtained for the eight sample strips were averaged to determine thetensile strength of the tissue.

Basis Weight

Using a dye and press, six 76.2 mm by 76.2 mm square samples were cutfrom a 1-ply product being careful to avoid any web perforations. Thesamples were placed in an oven at 105 deg C. for 5 minutes before beingweighed on an analytical balance to the fourth decimal point. The weightof the sample in grams was divided by (0.0762 m)² to determine the basisweight in grams/m².

Caliper Testing

A Thwing-Albert ProGage 100 Thickness Tester, manufactured by ThwingAlbert of West Berlin, N.J. was used for the caliper test. Eight 100mm×100 mm square samples were cut from a 1-ply product. The samples werethen tested individually and the results were averaged to obtain acaliper result for the base sheet.

Example 1

A 1-ply creped tissue web was produced on a Through Air Dried papermachine with a triple layer headbox and dual TAD drums, with the tissueweb having the following product attributes: Basis Weight 20.8 g/m²,Caliper 0.305 mm, MD tensile of 69.7 N/m, CD tensile of 43.7 N/m, an MDstretch of 22.4%, a CD stretch of 8.5%, and a 96 TSA.

The tissue web was multilayered with the fiber and chemistry of eachlayer selected and prepared individually to maximize product qualityattributes of softness and strength. The first exterior layer, which wasthe layer that contacted the Yankee dryer, was prepared using 100%eucalyptus with 0.25 kg/ton of a synthetic polymer dry strength agentDPD-589 (Ashland, 500 Hercules Road, Wilmington Del., 19808). Theinterior layer was composed of 40% northern bleached softwood kraftfibers, 60% eucalyptus fibers, and 0.75 kg/ton of T526,softener/debonder (EKA Chemicals Inc., 1775 West Oak Commons Court,Marietta, Ga., 30062). The second exterior layer was composed of 40%northern bleached softwood kraft fibers, 60% eucalyptus fibers and with1.875 kg/ton of a synthetic polymer dry strength agent DPD-589 at 3.0kg/ton. The softwood was refined at 30 kwh/ton to impart the necessarytensile strength.

The fiber and chemicals mixtures were diluted to a solids of 0.5%consistency and fed to separate fan pumps which delivered the slurry toa triple layered headbox. The headbox pH was controlled to 7.0 byaddition of sodium bicarbonate to the thick stock before the fan pumps.The headbox deposited the slurry to a nip formed by a forming roll, anouter forming wire, and inner forming wire where the wires were runningat a speed of 1060 m/min. The slurry was drained through the outer wire,which was a KT194-P design supplied by Asters Johnson (4399 CorporateRd, Charleston, S.C.), to aid with drainage, fiber support, and webformation. When the fabrics separated, the web followed the innerforming wire and was dried to approximately 27% solids using a series ofvacuum boxes and a steam box.

The web was then transferred to a structuring fabric running at 1060m/min with the aid of a vacuum box to facilitate fiber penetration intothe structuring fabric to enhance bulk softness and web imprinting. Thestructuring fabric included a layer made from a netted tube of extrudedpolymer with a thickness of 0.5 mm, as shown in FIG. 1, with openingsbeing regularly recurrent and distributed in the longitudinal (MD) andcross direction (CD). This layer was the structuring layer of thefabric. The openings were circular with a diameter of 0.63 mm. The MDaligned portion of the netting of the layer extended 0.16 mm above thetop plane of the CD aligned portion of the netting of the layer. Thewidth of the MD aligned portion of the netting of the layer was 0.26 mm.The width of the CD aligned portion of the netting of the layer was 0.46mm. The layer was supported by woven fabric layer, which was a ProluxN005, 5 shed 1, 3, 5, 2, 4 warp pick sequence woven polymer fabricsanded to 27% contact area, supplied by Albany (216 Airport DriveRochester, N.H., USA) with a caliper of 0.775 mm. The two layers werelaminated together using ultrasonic welding.

The web was dried with the aid of two TAD hot air impingement drums to81% moisture before transfer to the Yankee dryer. The web was held inintimate contact with the Yankee surface using an adhesive coatingchemistry. The Yankee dryer was provided steam at 300 kPa while theinstalled hot air impingement hood over the Yankee dryer blew heated airat 125 deg C. The web was creped from the Yankee dryer at 13.2% crepe at98.2% dryness using a steel blade at a pocket angle of 90 degrees.

Example 2

A 1-ply creped tissue web was produced on a Through Air Dried papermachine with a triple layer headbox and dual TAD drums, with the tissueweb having the following product attributes: Basis Weight 20.6 g/m²,Caliper 0.380 mm, MD tensile of 68.8 N/m, CD tensile of 37.9 N/m, and MDstretch of 21.1%, a CD stretch of 10.8%, and a 97.1 TSA.

The tissue web was multilayered with the fiber and chemistry of eachlayer selected and prepared individually to maximize product qualityattributes of softness and strength. The first exterior layer, which wasthe layer that contacted the Yankee dryer, was prepared using 75%eucalyptus and 25% northern bleached softwood kraft fibers with 1.25kg/ton of glyoxylated polyacrylamide, Hercobond 1194 and 0.25 kg/ton ofa polyvinylamine retention aid, Hercobond 6950 (Solenis, 500 HerculesRoad, Wilmington Del., 19808) and 0.75 kg/ton of Redibond 2038(Ingredion 5 Westbrook Corporate Center Westchester, Ill. 60154). Theinterior layer was composed of 25% northern bleached softwood kraftfibers, 75% eucalyptus fibers, and 0.75 kg/ton of T526, asoftener/debonder (EKA Chemicals Inc., 1775 West Oak Commons Court,Marietta, Ga., 30062) and 1.25 kg/ton of Hercobond 1194. The secondexterior layer was composed of 100% northern bleached softwood kraftfibers with 2.25 kg/ton of Redibond 2038 and 0.25 kg/ton of Hercobond6950. The softwood was refined at 13 kwh/ton to impart the necessarytensile strength.

The fiber and chemicals mixtures were diluted to a solids of 0.5%consistency and fed to separate fan pumps which delivered the slurry toa triple layered headbox. The headbox pH was controlled to 7.0 byaddition of sodium bicarbonate to the thick stock before the fan pumps.The headbox deposited the slurry to a nip formed by a forming roll, anouter forming wire, and inner forming wire where the wires were runningat a speed of 1060 m/min. The slurry was drained through the outer wire,which was a KT194-P design supplied by Asten Johnson (4399 Corporate Rd,Charleston, S.C.), to aid with drainage, fiber support, and webformation. When the fabrics separated, the web followed the innerforming wire and was dried to approximately 27% solids using a series ofvacuum boxes and a steam box.

The web was then transferred to a structuring fabric running at 1060m/min with the aid of a vacuum box to facilitate fiber penetration intothe structuring fabric to enhance bulk softness and web imprinting. Thestructuring fabric included a layer made from a netted tube of extrudedpolymer with a thickness of 0.7 mm, as shown in FIG. 1, with openingsbeing regularly recurrent and distributed in the longitudinal (MD) andcross direction (CD). This layer was the structuring layer of thefabric. The openings were circular with a diameter of 0.75 mm. The MDaligned portion of the netting of the layer extended 0.25 mm above thetop plane of the CD aligned portion of the netting of the layer. Thewidth of the MD aligned portion of the netting of the layer was 0.52 mm.The width of the CD aligned portion of the netting of the layer was 0.62mm. The layer was supported by woven fabric layer, which was a ProluxN005, 5 shed 1, 3, 5, 2, 4 warp pick sequence woven polymer fabricsanded to 27% contact area, supplied by Albany (216 Airport DriveRochester, N.H., USA) with a caliper of 0.775 mm. The two layers werelaminated together using ultrasonic welding.

The web was dried with the aid of two TAD hot air impingement drums toapproximately 80% moisture before transfer to the Yankee dryer. The webwas held in intimate contact with the Yankee surface using an adhesivecoating chemistry. The Yankee dryer was provided steam at 300 kPa whilethe installed hot air impingement hood over the Yankee dryer blew heatedair at 105 deg C. The web was creped from the Yankee dryer at 13% crepeat approximately 98% dryness using a steel blade at a pocket angle of 90degrees.

Comparative Example

A 1-ply creped tissue web was produced on a Through Air Dried papermachine with a triple layer headbox and dual TAD drums, with the tissueweb having the following product attributes: Basis Weight 20.4 g/m2,Caliper 0.336 mm, MD tensile of 76.3 N/m, CD tensile of 40.6 N/m, an MDstretch of 22.9%, a CD stretch of 10.1%, and a 90.9 TSA.

The tissue web was multilayered with the fiber and chemists of eachlayer selected and prepared individually to maximize product qualityattributes of softness and strength. The first exterior layer, which wasthe layer that contacted the Yankee dryer, was prepared using 75%eucalyptus and 25% northern bleached softwood kraft fibers with 1.25kg/ton of glyoxylated polyacrylamide, Hercobond 1194 and 0.25 kg/ton ofa polyvinylamine retention aid, Hercobond 6950 (Solenis, 500 HerculesRoad, Wilmington Del., 19808) and 1.25 kg/ton of Redibond 2038(Ingredion 5 Westbrook Corporate Center Westchester, Ill. 60154). Theinterior layer was composed of 25% northern bleached softwood kraftfibers, 75% eucalyptus fibers, and 0.75 kg/ton of T526, asoftener/debonder (EKA Chemicals Inc., 1775 West Oak Commons Court,Marietta, Ga., 30062) and 1.25 kg/ton of Hercobond 1194. The secondexterior layer was composed of 100% northern bleached softwood kraftfibers with 3.75 kg/ton of Redibond 2038 and 0.25 kg/ton of Hercobond6950. Softwood was refined at 16 kwh/ton to impart the necessary tensilestrength.

The fiber and chemicals mixtures were diluted to a solids of 0.5%consistency and fed to separate fan pumps which delivered the slurry toa triple layered headbox. The headbox pH was controlled to 7.0 byaddition of sodium bicarbonate to the thick stock before the fan pumps.The headbox deposited the slurry to a nip formed by a forming roll, anouter forming wire, and inner forming wire where the wires were runningat a speed of 1060 m/min. The slurry was drained through the outer wire,which was a KT194-P design supplied by Asten Johnson (4399 Corporate Rd,Charleston, S.C.), to aid with drainage, fiber support, and webformation. When the fabrics separated, the web followed the innerforming wire and was dried to approximately 27% solids using a series ofvacuum boxes and a steam box.

The web was then transferred to a structuring fabric running at 1060m/min with the aid of a vacuum box to facilitate fiber penetration intothe structuring fabric to enhance bulk softness and web imprinting. Thestructured fabric was a Prolux 005 design supplied by Albany (216Airport Drive Rochester, N.H. 03867 USA) and was a 5 shed design with awarp pick sequence of 1, 3, 5, 2, 4, a 17.8 by 11.1 yarn/cm Mesh andCount, a 0.35 mm warp monofilament, a 0.50 mm weft monofilament, a 1.02mm caliper, with a 640 cfm and a knuckle surface that was sanded toimpart 27% contact area with the Yankee dryer.

The web was dried with the aid of two TAD hot air impingement drums toapproximately 80% moisture before transfer to the Yankee dryer. The webwas held in intimate contact with the Yankee surface using an adhesivecoating chemistry. The Yankee dryer was provided steam at 300 kPa whilethe installed hot air impingement hood over the Yankee dryer blew heatedair at 110 deg C. The web was creped from the Yankee dryer at 13.0%crepe at approximately 98% dryness using a steel blade at a pocket angleof 90 degrees.

A comparison of Example 2 with the Comparative Example demonstrates thatthe use of an overlaid fabric of the present invention allows for use ofa lower temperature through the TAD section to arrive at the same sheetdryness. Example 1 differs from Example 2 and the Comparative Example inthat Example 1 used less hardwood. The furnish mixtures were the samebetween Example 2 and the Comparative Example and the basis weight andquality of the sheet were also very similar.

Now that embodiments of the present invention have been shown anddescribed in detail, various modifications and improvements thereon willbecome readily apparent to those skilled in the art. Accordingly, thespirit and scope of the present invention is to be construed broadly andnot limited by the foregoing specification.

The invention claimed is:
 1. A fabric or belt for a papermaking machinecomprising: a first layer that defines a web contacting surface, thefirst layer being made of extruded polymer and comprising: a pluralityof first elements aligned in a first direction; a plurality of secondelements aligned in a second direction and extending over the pluralityof first elements; and a plurality of open portions defined by theplurality of first and second elements; and a second layer made of wovenfabric that supports the first layer, wherein the first layer is bondedto the second layer so as to form an interface between the first andsecond layers that comprises bonded and unbonded portions and airflowchannels that extend in both a machine direction and a cross directionwithin a plane parallel to the first and second layers, and wherein thefabric or belt is a structuring fabric configured for use on apapermaking machine.
 2. The fabric or belt of claim 1, wherein the firstlayer extends only partially through the second layer.
 3. The fabric orbelt of claim 2, wherein the first layer extends into the second layerby an amount of 30 .mu.m or less.